U.S. patent application number 15/436089 was filed with the patent office on 2017-08-24 for inert gas generation system, and an aircraft fuel tank inerting system implementing said inert gas generation system.
The applicant listed for this patent is Zodiac Aerotechnics. Invention is credited to Christophe Claris.
Application Number | 20170239615 15/436089 |
Document ID | / |
Family ID | 55953246 |
Filed Date | 2017-08-24 |
United States Patent
Application |
20170239615 |
Kind Code |
A1 |
Claris; Christophe |
August 24, 2017 |
Inert Gas Generation System, And An Aircraft Fuel Tank Inerting
System Implementing Said Inert Gas Generation System
Abstract
An inert gas generation system from a flow of air, notably for
an inerting system for at least one aircraft fuel tank. The
generation system includes an air circuit having an air inlet, an
inert gas outlet, and a first and a second air separation module
arranged in series on the air circuit to deplete oxygen within the
air and to generate a nitrogen-enriched inert gas.
Inventors: |
Claris; Christophe;
(Saint-Just-Saint-Rambert, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zodiac Aerotechnics |
Roche la Moliere |
|
FR |
|
|
Family ID: |
55953246 |
Appl. No.: |
15/436089 |
Filed: |
February 17, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 71/028 20130101;
B01D 53/226 20130101; B64D 37/32 20130101; B64D 37/02 20130101;
B01D 2053/221 20130101 |
International
Class: |
B01D 53/22 20060101
B01D053/22; B64D 37/32 20060101 B64D037/32; B64D 37/02 20060101
B64D037/02; B01D 71/02 20060101 B01D071/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2016 |
FR |
1651294 |
Claims
1. An inert gas generation system from a flow of air, for an
inerting system for at least one aircraft fuel tank, said
generation system comprising an air circuit comprising an air
inlet, an inert gas outlet, and a first and a second air separation
module arranged in series on said air circuit to deplete oxygen
within the air and to generate a nitrogen-enriched inert gas.
2. The generation system according to claim 1, characterized in
that the air circuit comprises routing means for a portion of the
air flow upstream of the first module directly to the second
module, and routing means for the entire air flow downstream from
the first module directly to the inert gas outlet.
3. The generation system according to claim 2, characterized in
that the generation system further comprises a first valve and a
second valve arranged on the air circuit between the first module
and the second module, the first valve being connected to the gas
outlet by a first bypass circuit, and the second valve being
connected to the air circuit upstream of the first module by a
second bypass circuit.
4. The generation system according to claim 3, characterized in
that the valves are flow control valves.
5. The generation system according to claim 3, characterized in
that the valves are pressure control valves.
6. The generation system according to claim 1, characterized in
that the first and second air separation module comprise zeolite
membranes.
7. The generation system according to claim 6, characterized in
that the size of the zeolite membranes of the first module is
different from the size of the zeolite membranes of the second
module.
8. An inerting system for at least one aircraft fuel tank, said
system comprising at least one inert gas generating system supplied
with bleed air diverted from at least one engine, air from a
passenger cabin, or both air diverted from at least one engine and
air from the passenger cabin and distribution means for the inert
gas to at least one fuel tank connected to the inert gas generation
system, said inerting system being characterized in that the inert
gas generation system complies with claim 1.
Description
FIELD OF THE INVENTION
[0001] This invention relates to the art of inert gas generation
systems, notably used in inerting systems for at least one fuel
tank of an aircraft such as an airplane, a helicopter or
similar.
BACKGROUND OF THE INVENTION
[0002] In the art of aeronautics, the use of inerting systems is
well known for the generation of an inert gas, such as nitrogen or
any other inert gas such as carbon dioxide, and for introducing
said inert gas into fuel tanks for safety reasons in order to
reduce the risk of explosion from said tanks.
[0003] A conventional, prior art inerting system typically includes
an on board inert gas generation system (OBIGGS) supplied with air,
for example with bleed air diverted from at least one engine. The
bleed air diverted from at least one engine is currently the most
widely used model. In such a system, the bleed air is typically
routed from one or more engines at the opening known as the
intermediate pressure port and/or the opening known as the high
pressure port, depending on the flight situation. It should be
noted that the use of bleed air for the air conditioning is
advantageous because the bleed air has a relatively high pressure,
as well as a relatively high temperature, such that the air can be
adjusted to a wide range of desired pressure and temperature
settings. The OBIGGS is connected to the airplane fuel tank and
separates oxygen from the air.
[0004] An OBIGGS typically comprises an air separation module, or
several modules arranged in parallel, containing for example
zeolite membranes through which an air flow is forced. Due to the
different mass transfer rates for nitrogen and oxygen, the system
splits the air flow such that an air flow with high nitrogen
content and an air flow with high oxygen content are obtained. The
air fraction enriched with nitrogen, considered to be the inert
gas, is routed into fuel tanks such that the mixture of air and
kerosene vapor present at this location is displaced and discharged
from the tanks. The air fraction enriched with oxygen may be
reintroduced into the passenger cabin after having been treated
using appropriate means and/or into the reactors' combustion
chamber to improve combustion. The devices required for this
process such as compressors, filters, and air or water cooling
modules or similar are integrated into the inerting system.
[0005] When the ratio between fuel and oxygen in the empty part of
the tank is below the ignition limit defined in accordance with the
Federal Aviation Administration (FAA) requirements detailed in
AC25.981-2A dated Sep. 19, 2008 and entitled "FUEL TANK
FLAMMABILITY REDUCTION MEANS" and its appendices, no spontaneous
ignition may occur. From the foregoing, inerting a fuel tank
notably consists in injecting an inert gas in order to maintain the
level of oxygen present within said tank below a certain threshold,
for example 12%.
[0006] The inert gas generation systems known in the prior art
comprise at least two air separation modules, which are arranged in
parallel in order to generate and deliver a nitrogen-enriched gas
with desired purity, in terms of residual oxygen concentration, and
desired flow rate.
[0007] The inerting system preferably comprises a flow control
valve installed downstream from the air separation modules, in
order to modulate the type of flow sent to the tanks to suit the
aircraft flight phase.
[0008] A low flow modulation rate, for example from 0.45 to 0.90
kg/min, allows for an inert gas of very high quality to be
generated, notably comprising about 3% oxygen. This low flow mode
is typically used during the stable phases of the aircraft, for
example during the ground or cruising phases, which require
relatively low inert gas flow rates.
[0009] In descent mode, the inerting system tends to use a high
flow rate mode, for example from 0.68 to 1.36 kg/min, for which the
flow rate of the inert gas sent to the tanks is high but the
quality and purity levels are lower, notably of about 13%
oxygen.
[0010] The main drawback of inert gas generation systems known in
the prior art is their size. In fact, the arrangement of the air
separation modules results in a generation system that is
oversized, for example in terms of the number of modules and
filtration components, in relation to the actual flight phase need,
which in turn causes excessive consumption of kerosene and an
increase in the weight of the aircraft.
SUMMARY OF THE INVENTION
[0011] One of the objects of the invention is therefore to remedy
these drawbacks by proposing an inert gas generation system that
allows for an inert gas of high quality, to be generated notably in
terms of purity, and low oxygen content.
[0012] Another object of the invention is to provide an inert gas
generation system that can be adjusted to the needs and flight
phase of the aircraft.
[0013] To this end, and according to the invention, an inert gas
generation system was developed from a flow of air, notably for an
inerting system for at least one aircraft fuel tank, remarkable in
that it comprises an air circuit comprising an air inlet, an inert
gas outlet, and a first and a second air separation module arranged
in series on said air circuit to deplete oxygen in the air and
generate a nitrogen-enriched inert gas.
[0014] The air separation modules are arranged in series such that
they allow for an inert gas of very high purity to be generated,
i.e., with a very low oxygen content, notably of about 3%. In
addition, smaller-sized separation modules may be developed in
order to achieve performance similar to a system with larger
separation modules and arranged in parallel. The integration of the
inert gas generation system into the inerting system of an aircraft
is therefore facilitated.
[0015] In a particularly advantageous embodiment of the invention,
the air circuit comprises routing means for a portion of the air
flow, upstream of the first module, directly to the second module,
and routing means for the entire air flow, downstream from the
first module, directly to the inert gas outlet.
[0016] It is therefore possible to change the arrangement of the
air separation modules from series to parallel in order to suit the
flight phase and actual inert gas quantity and quality
requirements.
[0017] This invention allows the inert gas flow to be modulated in
an alternative manner to the high flow/low flow modulation commonly
used, by means of a method that uses air separation modules in
series or in parallel.
[0018] Thus, this invention makes it possible to downsize the
filtration equipment, such as the ozone converter and the
particulate filter, and to use the air separation modules at a
relatively constant flow rate which notably has advantages with
respect to the thermal control of the system. The air preparation
system of the inerting system may also be downsized.
[0019] Of particular interest for the invention are large inerting
systems comprising more than two air separation modules.
[0020] In a particular embodiment, the generation system comprises
a first valve and a second valve arranged on the air circuit
between the first module and the second module, the first valve
being connected to the gas outlet by a first bypass circuit, and
the second valve being connected to the air circuit upstream of the
first module by a second bypass circuit. The valves used may be
flow control or pressure control valves.
[0021] The air separation modules may be of any type. The first and
second air separation modules preferably comprise zeolite membranes
with sizes that may differ from one module to another.
[0022] The invention also relates to an inerting system for at
least one aircraft fuel tank. In a manner known in the prior art,
the system comprises at least one inert gas generation system
supplied with bleed air diverted from at least one engine and/or
air from a passenger cabin and/or air from outside the aircraft via
an air preparation system that uses a compressor, and distribution
means for the inert gas to the fuel tank(s) connected to the inert
gas generation system.
[0023] According to the invention, the inerting system is
remarkable in that the inert gas generation system complies with
the above characteristics.
[0024] Thus, when the aircraft tanks require a high inert gas flow
rate, particularly during the descent phase of the aircraft, the
invention allows the air separation modules to be changed to a
series arrangement such that the inert gas is of a higher
quality.
[0025] In contrast, when the tanks require a low inert gas flow
rate, the inert gas with a low flow rate is already of high quality
such that the air separation modules may be used in series or in
parallel as needed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Further advantages and features will become clearer from the
following description, given by way of a non-limiting example, of
the inert gas generation system according to the invention, with
reference to the accompanying drawings in which:
[0027] FIG. 1 is a schematic view of an inert gas generation system
according to the invention;
[0028] FIG. 2 is a schematic view showing an inerting system
according to the invention;
[0029] FIG. 3 is a schematic view similar to that of FIG. 1,
showing the series arrangement of the air separation modules;
[0030] FIG. 4 is a schematic view similar to that of FIG. 1,
showing the parallel arrangement of the air separation modules.
DETAILED DESCRIPTION OF THE INVENTION
[0031] In reference to FIG. 1, the invention relates to an inert
gas generation system (1) comprising an air circuit (2) to deplete
oxygen in order to generate a nitrogen-enriched inert gas.
[0032] In reference to FIG. 2, the generation system (1) is notably
intended to be used in an inerting system (11) for at least one
aircraft fuel tank (12). To this end, the inert gas generation
system (1) comprises an air inlet (3) supplied with bleed air
diverted from at least one engine and/or air from a passenger cabin
and/or air from outside the aircraft via an air preparation system
(14) that uses a compressor, and an inert gas outlet (4) connected
to distribution means (13) for the inert gas to the fuel tank(s)
(12). The generation system (1) also comprises an oxygen-enriched
gas outlet (15).
[0033] The inerting system (11) allows an inert gas to be generated
and introduced into said aircraft fuel tank(s) (12) for safety
reasons in order to reduce the risk of explosion from said tanks.
The injected inert gas aims to render the fuel tank(s) (12) inert,
i.e., allows the level of oxygen present within said tank(s) to be
reduced, and notably to maintain this level below a certain
threshold, preferably less than 12%.
[0034] In reference to FIG. 1, the inert gas generation system (1)
comprises at least two air separation modules (5, 6), comprising
for example zeolite membranes through which the air is forced such
as to obtain an inert gas with a high nitrogen content and an inert
gas with a high oxygen content.
[0035] According to the invention, the air circuit (2) of the inert
gas generation system (1) allows the two air separation modules (5,
6) to be connected together, and comprises arrangements for
selectively routing, upstream of the first module (5), a portion of
the air flow directly to the inlet of the second module (6), and
arrangements for selectively routing, downstream from the first
module (5), the entire air flow directly to the inert gas outlet
(4).
[0036] To this end, the air circuit (2) comprises two valves (7, 8)
arranged between the first and second air separation module (5, 6).
A first valve (7) is connected directly to the gas outlet (4) via a
first bypass circuit (9), and a second valve (8) is connected to
the air circuit (2) upstream of the first air separation module (5)
via a second bypass circuit (10).
[0037] The invention therefore allows the arrangement of the air
separation modules (5, 6) to change from series to parallel.
[0038] When the aircraft fuel tanks require a high inert gas flow
rate, notably during a non-stable phase of the aircraft such as the
descent phase, the air separation modules (5, 6) are changed to a
series arrangement by the actuation of the valves (7, 8) in order
to obtain a high inert gas flow rate while ensuring that said inert
gas is of a high quality and has a low oxygen content of about
3%.
[0039] To this end, and in reference to FIG. 3, the valves (7, 8)
are switched from a series control position wherein the air flow
circulating within the air circuit (2) crosses the first air
separation module (5), passes through the first and second valve
(7, 8), crosses the second air separation module (6), and is
discharged through the inert gas outlet (4) to be distributed and
injected into the tanks.
[0040] The series arrangement of the air separation modules (5, 6)
is also possible during the cruising phase of the aircraft in order
to allow the sizing of the filtration components of the inert gas
generation system (1) to be optimized.
[0041] Alternatively, when the tanks require a low inert gas flow
rate and depending on the need or the flight phase, the air
separation modules (5, 6) are changed to a parallel arrangement by
the actuation of the two valves (7, 8).
[0042] To this end, and in reference to FIG. 4, the valves (7, 8)
are switched to a parallel control position therein from the air
inlet (3): [0043] a first portion of the air flow circulating in
the air circuit (2) crosses the first air separation module (5) to
the first valve (7) which then routes the first portion of the air
flow in the first bypass circuit (9) and directly to the inert gas
outlet (4) without passing through the second separation module
(6); [0044] a second portion of the air flow is routed by the
second valve (8) in the second bypass circuit (10) and directly to
the inlet of the second separation module (6), without passing
through the first separation module (5), and crosses said second
module (6) to the inert gas outlet (4).
[0045] According to the invention, inert gases with similar
purities may be obtained with different flow rates depending on the
arrangement in series or in parallel of the air separation modules
(5, 6). This is particularly advantageous when the generation of an
inert gas with constant quality and purity, and with different flow
rates is required.
[0046] The invention is particularly advantageous when the valves
(7, 8) used are pressure control or flow control valves.
[0047] Of course, without departing from the scope of the
invention, other embodiments are possible with a generation system
(1) comprising more than two air separation modules (5, 6) in order
to generate an inert gas with a purity that meets the needs,
notably for example in the context of closed loop control
applications. The key aspects of the invention are the provision of
an inert gas generation system (1) with air separation modules (5,
6) arranged in series, and the ability to advantageously change, as
needed, said air separation modules (5, 6) to a parallel
arrangement. Alternatively, with more than two air separation
modules (5, 6), other possible arrangements are: an arrangement
with air separation modules (5, 6) in series and in parallel, and
an arrangement with air separation modules (5, 6) in series only.
In addition, and to better adjust to the quantity and quality
requirements of the inert gas, the size of the zeolite membranes of
the first module (5) may differ from the size of those of the
second module (6).
[0048] The inert gas generation system (1) according to the
invention may also be used at the output (15) of a generation
system (1) for extracting the residual nitrogen in said
oxygen-enriched gas and improving the yield of said system.
[0049] Similarly, since an inert gas generation system (1) also
generates an oxygen-enriched gas, the invention may be used to
generate an oxygen-enriched gas with air separation modules
selectively arranged in series or in parallel.
* * * * *